auth: Ignore empty initial response strings.

--HG--
branch : HEAD

diff --git a/src/auth/auth-request-handler.c b/src/auth/auth-request-handler.c
index 7e30470a6c70dda6de83f25aa16e1d792a6bef79..20956f5ceadc72ddb87bf37e889d31a059f59450 100644 (file)
--- a/src/auth/auth-request-handler.c
+++ b/src/auth/auth-request-handler.c
@@ -362,7 +362,10 @@ bool auth_request_handler_auth_begin(struct auth_request_handler *handler,
                return TRUE;
        }
 
-       if (initial_resp == NULL) {
+       /* Empty initial response is a "=" base64 string. Completely empty
+          string shouldn't really be sent, but at least Exim does it,
+          so just allow it for backwards compatibility.. */
+       if (initial_resp == NULL || *initial_resp == '\0') {
                initial_resp_data = NULL;
                initial_resp_len = 0;
        } else {